将另一页上的下拉列表的默认值设置为等于上一页上选择的值

Question

I have the following code that generates a dropdown list. I want the value selected to be the default value of the same drop-down list on another page. The code I am using to generate the drop-down list is area_index.php:

// Write out our query.
    $query = "SELECT * FROM hub";
    // Execute it, or return the error message if there's a problem.
    $result = mysql_query($query) or die(mysql_error());

    $dropdown = "<select name='hub'>";
    while($row = mysql_fetch_assoc($result)) {

    $dropdown .= "
<option value='{$row['name']}'>{$row['name']}</option>";
    }
    $dropdown .= "
</select>";

?>
<form method="post" align= "right">
<table >
    <tr>
        <td>Select the Hub for which you want to add and area: </td>
        <td><?php echo $dropdown; ?></td>
    </tr>
    <tr>
        <td>&nbsp;</td>
        <td><input type="submit" name="submit" value="Add" align= "right" /></td>
    </tr>

</table>

I want to display the same drop-down list in my page called area_view.php but the default value of the drop-down list must be equal to the selected value.

The variable in area_index.php used is $hub_name = $_POST['hub'];

Answer 1

Change your while loop to this:

while($row = mysql_fetch_assoc($result)) {
    $dropdown .= "
<option value='{$row['name']}'" . ($row['name'] == $_POST['hub'] ? "selected" : "") . ">{$row['name']}</option>";
}

This checks to see if the value you're passing as $_POST['hub'] from the previous page equals the value of $row['name'] for each option being added. For the one that's equal, it will add the attribute selected, which will cause the browser to show that option as the selected one.